The present disclosure relates to electronic circuits and methods, and in particular, to wideband bias circuits and methods.
CMOS transistors are occasionally stacked in order to split the voltage swing across multiple devices for reliability purposes. FIG. 1 illustrates a typical amplifier stage. An input signal is applied to the gate of a bottom MOS device 101 (e.g., in common source (CS) configuration). The top cascode device 102 (in common gate (CG) configuration) is commonly biased using a resistive element (e.g., resistor ladder including resistors 103 and 104) between the supply and ground. The cascode device has a gate capacitance 105 that holds a bias voltage. Traditional approaches for biasing nodes in a circuit from a supply voltage using resistive element are satisfactory if the supply voltage maintains a constant (or nearly constant) value. However, in applications where the supply voltage changes, the resistances and capacitances may impair the operation of the circuit.